1. Field of the Invention
The invention generally relates to an amplifier apparatus, and more particularly, to an audio amplifier apparatus capable of inhibiting pop noise.
2. Description of Related Art
When an electronic product is turned on or off, disturbing pop noise is usually given off from its loudspeaker. This pop noise is generated when the voltage on the output terminal of an audio amplifier apparatus for driving the loudspeaker changes drastically and accordingly a spike current is produced. Besides the discomfort brought to the user, sometimes damages may be caused on highly sensitive elements in the loudspeaker by a large spike current. Thereby, how to eliminate pop noise has become a major issue in the design of audio amplifier apparatuses.
Conventionally, an additional soft charge circuit is usually disposed for soft charging the output terminal of the audio amplifier apparatus, so as to gradually increase the voltage level on the output terminal of the audio amplifier apparatus and reduce the pop noise produced when the electronic product is turned on or off. However, when the soft charge circuit finishes its soft charging operation and the loudspeaker switches to its normal operation state, the sudden activation of the audio amplifier apparatus may also cause some pop noises. In addition, the soft charging operation may slow down the boot-up of the audio amplifier apparatus. Accordingly, the quality of the audio amplifier apparatus cannot be effectively improved.